This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We have demonstrated excellent results in diagnosing normal, two types of benign lesions and malignant lesions on freshly excised tissue using Raman spectroscopy. The study thus supported moving the technique to a clinical setting for further testing of its efficacy in breast cancer diagnosis. As a result, we pursued clinical study. We collected data in the University Hospitals of Cleveland pathology suite, typically within half an hour of excision during partial and whole mastectomy. The main goals of this study was to validate our in vitro diagnostic algorithm on a large data set which closely mimics an in vivo environment and to elucidate differences between the Raman spectra of fresh-frozen and fresh breast tissues. Another clinical study is scheduled. The main goal of this study is expanding our diagnostic algorithm to include pathologies not seen previously in our studies, such as ductal carcinoma in situ and microcalcifications.